Recently, as the density of circuits incorporated into a semiconductor device is increased, a semiconductor device is known that performs data transmission through electromagnetic induction between coils each formed on each of multiple laminated semiconductor chips. On such a semiconductor device, a coil formed on one of semiconductor chips generates a magnetic field signal that induces a signal, proportional to a differential value of a current signal that is input to the transmission coil, in a coil formed on another semiconductor chip. This induced signal is received to perform signal transmission between chips in non-contact mode.
For example, Patent Document 1 describes an integrated circuit device in which two or more circuit chips, each of which forms an integrated circuit, are laminated and the integrated circuits formed on the circuit chips are electromagnetically coupled by electromagnetic induction coils. Patent Document 2 describes a signal transmission device, which is a three-dimensional integrated circuit composed of vertically laminated integrated circuit chips, for transmitting a signal through induction using the coupling inductance M between one part of the vertically integrated circuit in one chip layer Ln and the other part of the vertically integrated circuit in another chip layer Ln+x. In addition, Non-Patent Document 1 describes a semiconductor device in which multiple semiconductor chips are laminated, the coils formed on the semiconductor chips are vertically arranged one on top of the other in the same position, and the transmission circuit and the reception circuit are arranged near the coils for signal transmission between the upper semiconductor chip and the lower semiconductor chip.
In the devices described above, the waveform of the current signal flowing in the transmission coil is a steep, narrow pulse-width waveform similar to that of a signal that flows only at rise time and fall time of a rectangular wave that is input to the transmission device. On the other hand, because differential value of the input magnetic field is induced as a voltage in the reception coil according to the Faraday's law of induction, a differential signal of the current signal waveform flowing in the transmission coil is induced. As a result, the voltage signal having a narrow pulse-width, steep peak is input to the reception device.
Normally, there are various noise sources inside and outside a semiconductor device. For example, a semiconductor chip includes many logic circuits, and the signal transmission among the circuits is performed by the charge and discharge of a capacitor at the input of a reception circuit. It is known that the current that flows at that time has a waveform very similar to the waveform of the current signal flowing in the transmission coil described above. If a current having this waveform is introduced into the reception coil as a noise, it is very difficult in principle to separate between the noise and the reception signal because the voltage signal generated by the noise is very similar to the voltage signal based on the regular reception signal induced in the reception coil.
To solve this problem, Patent Document 3 discloses a transmission method and an interface circuit that are noise-resistant and, even if a noise is introduced, transmit signals without being affected by the noise. The method described in Patent Document 3 supplies the driving voltage waveform, such as the one shown in FIG. 17A, to the transmission coil. On the other hand, the magnetic field signal, which is output from the transmission coil, is a triangular wave or an almost triangular wave as shown in FIG. 17B, and the voltage waveform induced in the reception coil shown in FIG. 17C may be changed to a reception signal having a wide pulse-width waveform. As a result, the signal may be distinguished clearly from a noise signal that has a narrow-width voltage waveform.
Patent Document 1:
Japanese Patent Kokai Publication No. JP-H07-221260A
Patent Document 2:
Japanese Patent Kokai Publication No. JP-H08-236696A
Patent Document 3:
International Publication WO07/029435A1
Non-Patent Document 1:
Noriyuki Miura, et al., “Analysis and Design of Transceiver Circuit and Inductor Layout for Inductive Inter-chip Wireless Superconnect”, IEEE 2004 Symposium on VLSI Circuits Digest of Technical Papers, pp. 246-249(2004).